Hope your DH understand that many babies are taking finger foods when they are 8 months old, no matter their parents believe BLW or not. Depriving them the opportunty to self-feed themselves is not good for the development of their new skills (pincer grasp and chewing). Many babies are too get used to purees that they have to wean pureed food when they are older!
I am also a worrier-father (my DW would consider me the world's top worrier). I still choose BLW because I know that spoon-feeding is conducive to choking as well if the food goes to the back of the mouth before the baby has developed the ability to process it (this often happens especially when feeding is done in a hurry). On the contrary, BLW can be very safe because the baby is not forced (or even made) to eat (+ common senses of safety applied to all babies e.g. no peanuts or other round hard or slippery food, never leaving the baby unattended when eating).
To end, I just want to say a few words of concern about your nanny. Since she is too accustomed to spoon-feeding if you really want her to practice BLW, please make sure that she knows the differnece between gagging and choking and knows what to do when seeing your baby gags or chokes. The latter (very rare in BLW as mentioned) of course requires first aid. Some people are too afraid of gagging (in fact, afraid of giving control back to the baby) that whenever they see any sign of gagging they immediately put their fingers into the baby's mouth wanting to take the food out! This may only push the food to the further back part of the mouth and result in real choking. The core issue to me is, then, WHO carries out the BLW. Perhaps in your case it is only you at the moment when only you are eating together with your baby. Although it's not perfect but to me it is not a failure, just a temporary compromise between feeding, safety and unique family situation (and family pressure).